Overnight temp spike after eggs set?

Hello friends! Looking for some reassurance and truth talk regarding a dozen eggs of various breeds in a Hova-Bator 1620...

This is my first time ever using a "real" incubator, and many years since I had chickens or hatched any! My Dad built our shoe box incubator with a clip on desk lamp and old flannel shirts. It hatched many an egg, from chickens to sparrows during my childhood and never did I once hear him talk about "relative humidity" or "99.5 degrees". So this more scientific approach is hard to adjust to, when all my memories of hatching eggs are based on intuition!

Anyway, here's what I'm worrying about. Despite plugging in the incubator a week in advance to tweak the temp and humidity (it was running beautifully for three full days!), I put my eggs in around 5pm Tuesday night, and the temp dropped many degrees (normal, I know - I opened it, etc). So I waited a few hours and it seemed to come back up. (5pm tonight will be the end of the first 24 hours in the incubator.)

Yesterday afternoon, I had put water in one of the troughs of the plastic tray, which the instructions said to do for this model. But then, I was reading that you shouldn't put water in the tray and just use the ambient humidity, the "correct" amount of which was reported to be between 40% and 60% depending on the source I was reading. Well, my intuition told me that 60% on my newer analog hygrometer (digital was reading 48%) was too high, so I took some of the water out of the tray and repositioned my eggs for the night. I checked them at about 1:00am, and the temp was still a bit low after me having opened it to remove the water at about 11:30-midnight. I figured it would need a few hours to come back up.

Now I'm not sure if I accidentally turned the thermo control when I opened the lid, or what - but my partner woke me up at 6:30 to tell me the temp was 105!!!!!!! I jumped out of bed, took the lid off and tried to let the eggs cool a bit with the lid open for a few minutes. I read that one person cooled them in water, but I was afraid of washing the bloom off, so I just blew on them and left the lid off a bit. When I replaced the lid and read the therm a few minutes later, it was at 90 and going up slowly. That was maybe 7:30am, and It's been stable at 99-100 for the rest of the day. So I figure it may have been at 105 for maybe 2-3 hours overnight, factoring in how long the incubator takes to get to that temp and maintain it.

I'm nervous I cooked all my little chicken embryos. :( I have been reading all day and getting so many mixed messages about how I DEFINITELY killed them at 105, or how I DIDN'T kill them because it's 107 that will kill them in still air incubators... Or how 30 minutes of 105 can kill them, but then another saying 6 hours at 105 won't harm them... Or how they won't die but will live miserable deformed short lives if they can even get themselves out of the shell without suffocating. One source (which I read in such a loving, reassuring motherly voice in my head) told me that if it was a few hours, not to worry much because it takes quite a while to get the internal egg temp up to cell-destroying temperatures. I'm carrying this around with me in my brain hoping that's the case.

What are you experiences? Have you ever had a temp spike for several hours of 5 degrees or more and still have a good turn out? What was the result of live, healthy chicks vs deformed of dead chicks?

Of course I'll be candling in a few days to see if I can see anything in the lighter eggs (praying!). Could I candle sooner than 7 days to check? I'm preparing for disaster but any encouraging words would be appreciated!

I wish I could give you a definitive answer!!! The truth is---there is no way to tell 100% that they survived or not. You're right, sometimes science really does complicate things!
The embryos were in the very earliest stages of development when the temp spike happened--they did not even have a heartbeat yet. Embryos are the most fragile and sensitive in the first 7 days of incubation. However, a couple things:
1. It's a still air incubator, where temperature is "layered," in other words, it's hotter at the top of the incubator than the bottom and temperature does not raise or lower very fast. You could have only been at 105 for a matter of minutes--no way to tell. Lethal temperatures in a still air are around 107 (all depends on who you talk to!) Also, not all of the incubator was necessarily at 105 degrees---sometimes still air incubators can have temperature differences of +/- 5 degrees (that's why it's important to have multiple thermometers in different places in the incubator.)
2. I've never heard of short temperature spikes creating deformed chicks. I do know that a consistently too-high incubation temperature can cause deformities.
3. You can candle lighter eggs at day 4-5 to see if you can see any signs of life. Don't throw away any eggs until day 10 unless they're starting to ooze/smell.
4. A possible reason you had a temp spike like that is because you removed some of the water. Lowering humidity generally causes a raise in temperature, and vice versa.
5. It's a good thing you didn't cool them in water. Rapid temperature swings from very hot to cold are definitely not good.
Also as a note, still air incubators should run at about 102 degrees, not 99-100
Please let us know what happens! I understand the worries--I have nearly cooked embryos many a time (lethal temps in a forced fan incubator like mine are much easier to reach than in a still air). Edited by beetandsteet - 4/6/16 at 8:54pm